Vehicular forward viewing image capture system

ABSTRACT

A vehicular forward viewing image capture system includes an accessory module configured for attachment at an in-cabin side of a windshield of a vehicle, whereby the imaging sensor views through the windshield forward of the equipped vehicle. With the accessory module attached at the in-cabin side of the windshield, and while the vehicle is traveling along a road, a control processes captured image data to determine (i) presence of an object of interest viewed by the imaging sensor and (ii) location and/or movement of the object of interest viewed by the imaging sensor. The control, responsive to the processing of captured image data and responsive to vehicle data received via a vehicle communication bus, at least in part provides at least one selected from the group consisting of (a) traffic sign recognition, (b) traffic light status detection, (c) adaptive cruise control and (d) pedestrian detection.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/125,891, filed Sep. 10, 2018, now U.S. Pat. No. 10,787,116,which is a continuation of U.S. patent application Ser. No. 15/262,479,filed Sep. 12, 2016, now U.S. Pat. No. 10,071,676, which is acontinuation of U.S. patent application Ser. No. 14/164,682, filed Jan.27, 2014, now U.S. Pat. No. 9,440,535, which is a continuation of U.S.patent application Ser. No. 13/887,727, filed May 6, 2013, now U.S. Pat.No. 8,636,393, which is a continuation of U.S. patent application Ser.No. 13/452,130, filed Apr. 20, 2012, now U.S. Pat. No. 8,434,919, whichis a continuation of U.S. patent application Ser. No. 13/173,039, filedJun. 30, 2011, now U.S. Pat. No. 8,162,518, which is a continuation ofU.S. patent application Ser. No. 12/377,054, filed Feb. 10, 2009, nowU.S. Pat. No. 7,972,045, which is a 371 of PCT Application No.PCT/US2007/075702, filed Aug. 10, 2007, which claims the benefit of U.S.provisional applications, Ser. No. 60/845,381, filed Sep. 18, 2006; andSer. No. 60/837,408, filed Aug. 11, 2006, which are hereby incorporatedherein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to automatic headlamp control systems forvehicles and, more particularly, to automatic headlamp control systemsthat automatically adjust the high and low beam states of a vehicleheadlamp.

BACKGROUND OF THE INVENTION

Automotive forward lighting systems are evolving in several areasincluding the use of image-based sensors, typically referred to asAutomatic High Beam (AHB) control systems, to maximize the use of highbeam road illumination when appropriate, the use of steerable beamsystems, typically referred to as Adaptive Front Lighting (AFL) systems,to provide a greater range of beam pattern options particularly fordriving on curved roads or during turn maneuvers wherein the beampattern may be biased or supplemented in the direction of the curve orturn, and the combination of such AHB and AFL systems.

U.S. Pat. No. 6,097,023 (which is hereby incorporated herein byreference in its entirety) describes an automatic high beam controlsystem which utilizes an optical system, an image sensor, and signalprocessing including spectral, spatial and temporal techniques todetermine ambient lighting conditions, the road environment, and thepresence of other road users in order to automatically control theselection of the appropriate forward lighting state such that userforward vision is optimized while minimizing the impact of headlampcaused glare on other road users in all lighting conditions.

While AHB systems that utilize the features and concepts describedwithin the above identified U.S. patent have achieved performance levelsthat have resulted in considerable commercial success, it is desired toprovide additional features and techniques, which may increase theutility, improve the performance, facilitate the manufacture, andsimplify the installation of such systems.

SUMMARY OF THE INVENTION

The present invention provides an automatic headlamp control system thatis operable to automatically control or adjust the high beam state of avehicle's headlamps. The headlamp control system is operable to spreadout or de-focus a captured image to spread out the imaging of a lightsource so that an image of a distant light source is captured by atleast two pixels of an image array sensor. The image array sensor thusmay receive at least a portion of the light source (which may be a redtail light of a leading vehicle) on a red sensing pixel to enhance earlydetection of the distance tail light. The headlamp control system mayprovide enhanced control of the headlamps when the vehicle is drivenaround curves or bends in the road and may be operable in response to asteering wheel angle of the vehicle. The headlamp control system may beadjustable to align the optical axis of the imaging system with avehicle axis in response to detection of light sources and tracking ofmovement of the light sources as the vehicle travels along the road.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an accessory module and image sensingdevice and processor in accordance with the present invention;

FIG. 2 is a perspective view of the accessory module as seen through thewindshield of a vehicle;

FIG. 3 is a side elevation and partial sectional view of an imagesensing device useful with the present invention;

FIG. 4 is a plan view of an array of photo sensors of an image sensingdevice of the present invention;

FIG. 5 is a side elevation of a lens and image sensing device of thepresent invention;

FIG. 6 is another side elevation of a lens and image sensing devicesimilar to FIG. 5;

FIG. 7 is a schematic of a focused light source and de-focused lightsource as captured by pixels of an imaging sensor;

FIG. 8 is a side elevation of a lens and image sensing device of thepresent invention;

FIG. 9 is a chart showing the region of interest and average time gainedin low beam for several vehicles as the vehicles travel around differentdegrees of curvatures in the road;

FIG. 10 is a perspective view of a lens and image sensing device of thepresent invention;

FIGS. 11A-D are schematics of a quad of pixels of an image sensor inaccordance with the present invention;

FIG. 12 is a graph of a plurality of line profiles generated inaccordance with the present invention;

FIG. 13 is a graph of the slope of the line profiles of FIG. 12;

FIG. 14 is a graph of the edge slope vs. focal distance for the focusingalgorithm of the present invention;

FIG. 15A is a perspective view of a lens holder in accordance with thepresent invention; and

FIG. 15B is a plan view of the lens holder of FIG. 15A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to facilitate the description of features and enhancements,some specific configurations, to be reviewed in conjunction with thedrawings, is described below. It will be understood that the componentsand values described are for illustrative purposes and do not limit thescope of the disclosed invention.

With reference to FIG. 1, a vehicle 10 includes an automatic high beamcontrol system 11 made up of an optical system 12, an image sensor 13, adigital processor 14, a printed circuit board assembly 15, whichcontains all the necessary electronic components and interconnections tosupport operation of the image sensor 13 and digital processor 14, aconnection 16 to the vehicle wiring system, and a housing assembly oraccessory module or windshield electronics module 18.

The optical system 12 is held by features of the housing assembly 18 ina constrained spatial relationship with the image sensor 13, such thatan optical system axis 17 is perpendicular to the active plane of theimage sensor 13 and passes generally through its center point, and suchthat the distance between the optical system 12 and the image sensor 13may be adjusted to bring the optical system focal plane into apredetermined relationship with the active plane of the image sensor 13during the manufacturing process and thereafter locked in position. Thehousing assembly may utilize aspects of the modules or assembliesdescribed in U.S. Pat. Nos. 6,968,736; 6,877,888; 6,824,281; 6,690,268;6,672,744; 6,593,565; 6,516,664; 6,501,387; 6,428,172; 6,386,742;6,341,523; 6,329,925; 6,326,613; 6,250,148 and 6,124,886, and/or U.S.patent applications, Ser. No. 10/456,599, filed Jun. 6, 2003, now U.S.Pat. No. 7,004,593; Ser. No. 10/538,724, filed Jun. 13, 2005 andpublished Mar. 9, 2006 as U.S. Publication No. US-2006-0050018, and/orSer. No. 11/201,661, filed Aug. 11, 2005, now U.S. Pat. No. 7,480,149,and/or PCT Application No. PCT/US03/40611, filed Dec. 19, 2003; PCTApplication No. PCT/US03/03012, filed Jan. 31, 2003, and/or PCTApplication No. PCT/USO4/15424, filed May 18, 2004, and/or Irelandpatent applications, Ser. No. S2004/0614, filed Sep. 15, 2004; Ser. No.S2004/0838, filed Dec. 14, 2004; and Ser. No. S2004/0840, filed Dec. 15,2004, which are all hereby incorporated herein by reference in theirentireties.

The accessory module or housing assembly 18 includes an outer housing18a that is removably attached to an attachment plate 19, which isfixedly attached to the upper central region of the inside surface ofthe vehicle's windshield 20 such that the optical system axis 17 issubstantially horizontal and substantially parallel to the vehicle'sprincipal central axis. Preferably, the housing assembly 18 ispositioned at the windshield such that the light rays that pass throughthe optical system 12 to the image sensor 13 also pass through a portionof the vehicle's windshield swept by the vehicle's windshield wipersystem.

As shown in FIG. 3, optical system 12 includes a lens 31, or combinationof lenses or optical elements, with a focal length f (such as a focallength of, for example, about 4.5 mm), an optical stop, N (such as anoptical stop of, for example, about 1.8) and a spherical field of view(FOV) 34 (such as about 60 degrees). Optical system 12 also includes acylindrical lens holder 32, an infrared filter 33, and an image sensor13 positioned with its active surface perpendicular to optical axis 17.The infrared filter 33 facilitates the determination of color attributeswithin the visible light spectrum of objects within the monitored sceneby preventing near infrared energy, with a wavelength above about 750nm, from reaching the image sensor 13, and may be optionally placed atthe front (object side) or back (image side) of the optical system 12,between the optical system 12 and image sensor 13, or on the surface ofthe image sensor 13. The optical system and lens holder and sensor maybe located at an imaging sensor module, such as by utilizing aspects ofthe modules described in U.S. patent applications, Ser. No. 10/534,632,filed May 11, 2005, now U.S. Pat. No. 7,965,336, and/or U.S. provisionalapplication, Ser. No. 60/731,183, filed Oct. 28, 2005, which are herebyincorporated herein by reference in their entireties.

The image sensor 13 is preferably, but not limited to, a CMOSphotosensor array, such as part number MT9V125 produced by MicronCorporation, with 640 rows and 480 columns of 5.6 micron squarephotosensor elements and circuitry to measure the quantity of photonsthat impinge each photosensor element during a controllable period oftime. In the described configuration, the image sensor is oriented suchthat the 640 photosensor rows are horizontal and the 480 columns arevertical. Thus, in combination with the optical system 12, the imagesensor 13 has about a 48 degree horizontal field of view and about a 36degree vertical field of view.

In order to extract color information from the image or image data, oneof a number of filter types, each able to transmit a particular band ofwavelength, covers the active surface of each of the photosensorelements of the array. The most commonly used color filter pattern, andtherefore the most economically available as a standard feature of acommercially available image sensor, is the Bayer pattern in whicheither a blue, green or red pass filter is applied to the surface ofeach of the image sensor photosensor elements, such as shown in FIG. 4.Alternate rows of the photosensor elements may be covered by alternatingred and green filters and alternating blue and green filters such thatevery 2 by 2 block of photosensors within the array contains one redfilter, one blue filter and two diagonally opposite green filters. Sinceeach photosensor is filtered to measure only the blue, green or redlight energy content of the portion of the image formed by the opticalsystem at its active surface, it is necessary to combine the measuredvalues of filtered light from each of the photosensors of a 2 by 2 blocksuch that an interpolated red, green and blue color value (RGB) may beassigned to the center point of the block. The color value for each ofthe 2 by 2 blocks of the array is calculated, thus creating a 639 by 479array of color values with the same spacing as the photosensor array.This array of color picture elements is commonly termed a pixel array. Avariety of algorithms may be used to perform this interpolation,commonly termed demosaicing, and the particular algorithm may beselected depending on the particular the application, the desired finalimage quality and available computing power. For the AHB control systemdescribed herein, each pixel RGB value is derived by combining the redvalue, the average of the two green values, and the blue value of itsassociated four photosensor elements.

Optionally, the imaging device or module may comprise an imaging orintelligent headlamp control (IHC) module. For example, an intelligentheadlamp control module may have a dimensionally small cavity around alens holder 132 (FIGS. 15A and 15B), thus making threaded lens insertionvery difficult in an automated lens insertion situation. In order tomanufacture such an IHC module or lens holder 132, crush ribs 132 a maybe disposed or established at an interior surface of the barrel 132 b ofthe lens holder. By introducing vertical crush ribs to the barrel, theaxes of motion are decreased to one. In a threaded lens situation, theautomated lens insertion procedure could have as many as four axis ofmotion, thus increasing the cost of the module or system.

In order to accommodate the crush ribs, several lens modifications maybe needed, since a typical existing lens often has threads which maybind in the crush ribs. Thus, in order to accommodate the crush ribs,the lens may be manufactured or modified to have a smooth bore in orderto engage the control surfaces of the ribs evenly along the barrel ofthe lens holder.

The crush rib feature of the lens holder secures the lens duringmanufacture. However, it is desirable to apply an adhesive at the lensholder and lens to substantially permanently attach the lens to theplastic barrel of the lens holder. Lateral grooves around the barrel ofthe lens may be provided to allow the flow of adhesive around the lensfor a more uniform lens attachment or securement. Such grooves do notinterfere with the crush ribs during insertion as much as threads wouldand allow the flow of adhesive greater than a substantially smooth bore.

In order to control alignment and precision of the insertion of the lensdown the barrel (toward and away from the imager), a gripper may beprovided to isolate the head of the lens between two overlapping controlsurfaces that would hold the lens and control the toward and away (fromthe imager) motion during the focusing process.

The control surface of the printed circuit board (PCB) during the lensinsertion process preferably facilitates several criteria, bothmechanical and electrical, during such an automated process. The nestmay secure the imager board and backplate simultaneously in a repeatableorientation for lens insertion. The nest may also allow for electricalattachment to the ECU by way of pogo pins or the like during thefocusing process. It may also articulate in order to secure the ECUboard to the backplate after the focusing process.

In order to achieve enhanced AHB control system performance, it isdesirable to detect the tail lamp of a leading vehicle at about 200meters. The minimum tail light emitting surface area to meet legalrequirements is about 50 cm², which can be achieved using about an 80 mmdiameter circular or about a 71 mm square emitting surface. However, inmost cases, tail lamp designs are driven by vehicle stylingconsiderations and a desire on the part of vehicle manufacturers toexceed minimum requirements by a safe margin. Such design and stylingconstraints often result in tail lamp emitting surfaces with either ahorizontal or vertical dimension of at least about 125 mm.

Using the above described optical system 12 and imaging array 13, eachphotosensor element of the array has an effective horizontal field ofview FOVph and an effective vertical field of view FOVpv, where:

FOVph=FOVpv=48 degrees/640 pixels=0.075 degrees/pixel.

Thus, each photosensor element of the array subtends a region of avertical plane at distance R meters from the imager, which measures phby pv where:

ph=pv=FOVph×R×1000×PI/180 mm=1.309×R mm.

Thus, at a distance of about 200 m, the portion of the forward scenesubtended by each photosensor element of the array measures about 262 mmby about 262 mm, which is approximately twice the dimension of a typicaltail lamp of a vehicle. Since the dimension of the image of a tail lampat about 200 meters is in the order of half that of a photosensorelement, it is possible that the tail lamp image will lie entirely onthe blue and green detecting photosensor elements of a 2 by 2 block ofphotosensor elements, and thus may result in a pixel value with no redcontent. In order to assure that the red content of the image of thetail lamp at about 200 meters is measured and results in a red componentof the calculated pixel color value, it is desirable that the tail lampimage dimension be in the order of about one and a half times that of aphotosensor element, such that no matter where it lies or is received onthe photosensor array it will cover at least a portion of at least onered detecting photosensor.

This could be achieved by reducing the field of view of the opticalsystem by a factor of about three, resulting in a horizontal field ofview of about 16 degrees and a significant reduction in other aspects ofsystem performance. It could also be achieved by increasing the numberof photosensor elements in each row of the image sensor by a factor ofabout three, with a corresponding reduction of photosensor elementdimension, or by increasing the number of photosensor elements in eachrow of the image sensor by a factor of about three, maintaining thephotosensor element dimension, and changing the optical systemspecification in order to maintain about a 48 degree horizontal field ofview. However, this is typically not a practical solution due to thecost or availability of such image sensors and the cost of theadditional processing capacity required to handle the significantlyincreased amount of image data.

It is thus an aspect of the present invention to increase the effectivesize of the image at the image sensor of a tail lamp at 200 meters, sothat its presence and color may be detected, without changing theoptical system or image sensor and while maintaining the ability toperform other object detection tasks to support additional features andfunctions, such as described below.

The following analysis of the optical system contained within the AHBcontrol system will serve to explain the principles used to establish anoptimal configuration.

FIG. 5 shows an imaging device having a thin lens 31 with focal length fmm, effective diameter a mm, and optical stop N, where N=f/a. An objectplane OP, which is perpendicular to the optical axis of lens 31 and at adistance s mm from its optical center, and an image plane 13 a parallelto the object plane at a distanced mm from, and on the opposite side of,the optical center of lens 31. The focal length f is the distance fromthe optical center of lens 31 to the point at which light rays from adistant point on the optical axis 17 converge. Light rays that passthrough lens 31 behave according to the thin lens equation 1/s+1/d=1/f.Thus, an image of the point P on the object plane OP is in focus atpoint I on the image plane 13 a.

FIG. 6 shows the same configuration as FIG. 5 with the addition of apoint P′ at distance s′ from the optical center of the lens 31.According to the thin lens equation (1), a focused image of point P′would be formed at point I′ which is at distance d′ from the opticalcenter of the lens. However, since the image plane 13 a has remained atthe distance d from the lens, the light rays from point P′ continuethrough point I′ and diverge until they reach the image plane 13 aresulting in an unfocused image of point P′ with diameter C, commonlytermed the circle of confusion.

For a thin lens: 1/s+1/d=1/i f   (1)

or: d=f×s/(s−f)

similarly: d′=f×s′/(s′−f)

by similar triangles: C=a×(d−d′)/d′

by definition: a=f/N

by substitution: C=f ²×(s′−s)/N×s′×(s−f)   (2)

Consider now the object point to be replaced by a circular uniform lightsource of diameter D. When placed at point P, the image of the disc atthe image plane would appear as a focused disc of diameter D′ withuniform intensity (such as shown at A in FIG. 7). A plot of imageintensity across an extended diametral line would appear as line A′ witha step change from background image intensity to disc image intensity.When placed at point P′, the previously described circle of confusion,with diameter C, would be created at the image plane 13 a for each pointon the disc, resulting in an unfocused image of the disc with diameterD″, where D″=D′+C (such as shown at B in FIG. 7). A plot of imageintensity across an extended diametral line would appear as line B′ withgradual change from background intensity to full disc image intensityover a distance equal to the circle of confusion, C.

Rearranging equation (1) to solve for s:

s=f×s′×(C×N+f)/(C×N×s′+f ²)   (3)

For the optical system described above, f=4.5 mm and N=1.8. Thus,C=0.0056 mm, s′=200 m, and s=1.933 m. Thus, the same amount of lightenergy has been distributed over a greater image area. By focusing thelens to focus an image of an object P that is about 1.993 m from thelens, the defocused object P′ at about 200 m from the lens will bedefocused to have a diameter that will allow the image to be received bymore than one pixel of the imaging array sensor or camera. Such anexpanded image of the light source (by de-focusing the image of anobject at about 200 meters) will be received by more than one pixel andwill be at least partially received by a red sensing pixel so that thesystem can determine whether or not a distant light source is a redlight source and thus whether or not the distant light source may be ataillight of a leading vehicle.

Focusing or adjustment of the lens may be performed via any suitablefocusing means, such as a linear slide mechanism that has a highresolution motor and controller, such as an MX-80 miniature slide with aVix 250 IM motion controller commercially available fromParker-Hannifin. Such as slide mechanism and motor may provide aresolution of about 1 μm and a repeatability of about 2 μm orthereabouts. Such characteristics make good resolution possible acrossthe focus range so that the captured image data will illustrate orapproximate an enhanced or optimum focus value.

Once an image was loaded by the software, the image may be analyzed bymany different means including line profiles and color analysis. For theprocessing of the image data, a processor system or software, such asData Translation's DT Vision Foundry©, may be used to analyze the imagesusing software masks or regions of interest (ROI's). The exemplary DTVision Foundry© software provides an imaging software designed to assistmachine vision systems in operation, programming, and data management.

The imaging software was used to process image ROI's using a lineprofile tool. The line profile tool examines the pixel gain values whichthe line mask lays. The line profile tool graphically illustrates thegain values across the mask. It also may provide a data export toolwhich enables the user to view and manipulate the intensity valuesgathered from the imager.

Imager color values are independent to a color pixel. Four pixels in agrid pattern, as shown in FIG. 11A, are often referred to as a “quad”.The values taken from the imager are typically intensity or gain values(0 to 255) from the pixels in the quad. There are many different ways inwhich displays and compilers interpret the intensity values from theimager. The most straight forward way is to collect each pixel'sintensity value and compile it into a 64-bit RGGB image. This method ofcompilation yields enhanced resolution because all of the pixel data istransferred; however, the file sizes may be very large. Many softwaredesigners use compression techniques to keep the file sizes lower.

The first method of compression is to get the maximum pixel value fromthe green pixels in the quad. The second green pixel in the quad is setto the maximum green pixel's value. This method works well in mostapplications. However, since focus is directly related to the sharpnessof the edges of the target in an image, the green pixel values shouldnot be extended to allow the edge to appear sharper than it is. As shownby the edges B and C in FIGS. 11C and 11D, if the edge of the targetimage lies across the imager in a vertical orientation bisecting the twogreen pixels of the quad, the second green pixel is then set to themaximum green pixel. This allows for a false edge to be seen by theimage processing software. One way that the quad detects the edgecorrectly is if the edge of a target bisects the green pixels of thequad evenly, as shown by edge A in FIG. 11B. To counter this effect,software designers often average the green pixels together to allow thepixel to take into account the pixel effected by the edge of a targetimage.

While some visual resolution may be lost by averaging the green pixels,for matters of image processing the data is typically more telling. Ifthe target image edge falls on the imager, such as edge B or C of FIGS.11C and 11D, the value will be less than the maximum value because thegreen pixels in the quad are averaged. By examining the difference inintensity value of the quads either side of the averaged edge quad, theedge location within the quad can be approximated.

Focus is directly related to the sharpness of the edges of the targetimage. Optionally, two image processing tools may be used: a histogramand a line profile. After image data are captured and stored, theautomatic focus software processes the image data with a histogram tool.A histogram of a region of interest (ROI) in an image will illustrate,using a bar graph, the number of pixels at their respective intensityvalue. The theory behind using a histogram is that as a black and whitetarget image is processed, a more focused image would have more pixelsin extremes and fewer pixels in the medium intensity range. However, inorder to create an algorithm to focus the imager, a more perceivablepattern to predict the focal distance was needed.

Optionally, and desirably, the intelligent headlamp control (IHC) mayfocus by capturing individual picture frames and measuring a lineprofile through a target image consisting of several dark bars separatedby different spacing. After finding the line profiles across the target,the slope of the line profiles is calculated to find the sharpness ofthe edges of the target image. If the target image is sharp (in focus),the peak of the slope will be abrupt and large. If the edges of thetarget image are blurry, the peak of the slope will be smaller and lessabrupt (as can be seen with reference to FIG. 13).

Thus, a line profile tool may be implemented to examine the pixels in aone dimensional mask or line. Such a line profile tool charts theintensity values detected by the imager along the line mask, such asshown in FIG. 12. By using the line profile tool, the edges of thetarget image are able to be examined. The theory used for the lineprofile is that as the line mask crossed from a black to white or viceversa target area, the detected intensity value curve would have less ofa slope in an unfocused image than a more focused image. The imagingsoftware may include a derivative function to find the slope of the lineprofile as shown in FIG. 13.

To find the slope, the intensity value of the pixels in the line profilecan be calculated in several ways. However, in order to simplify thecalculation, the following method to find slope was derived:

${\frac{Y_{n} - ( Y_{n - 1} )}{X_{n} - ( X_{n - 1} )} = S_{n}};$

where Y is the intensity value of the pixels 1, 2, 3, 4 . . . n, and Xis the position of that pixel along the line profile.

Once the slope had been determined by the above equation, the maximumand minimum slopes from that image were recorded along with thereference distance away from the starting back focal length as shown inFIG. 14. As the images are processed, a pattern exists that referencesthe maximum and minimum slopes to focal length. This focal length curveis the basis of the software algorithm.

After the slope of the line profile has been plotted, the slope can beplotted against the back focal distance by finding the maximum andminimum slope. As shown in FIG. 14, the correlation between rising edgeslopes of several line profiles and back focal distances may bedetermined. Once near-focus has been achieved, the curve of FIG. 14provides a reference to the nominal back focal length and creates aquick focus procedure.

After creating several “Slope vs. Distance” curves, the tolerance rangefor the back focal distance may be approximately ±100 microns fromnominal. The tolerance specification given for the lens may be ±210microns. These tolerance stack-ups require an individual focus for eachlens to imager combination.

Using the same line profile slope plot as in FIG. 13, the pixel lengthof the target image can be found to verify magnification. Since the sizeof the target is critical in the IHC algorithm, the magnification needsto be verified during focus calculations. To verify the magnification ofthe lens, the distance, in pixels, is measured between the peak risingedge slope and the peak falling edge slope taken from a target near thecenter of the field of view. That pixel length is verified against apredetermined value for that target. The production target has not beendesigned making that pixel length variable to the target.

The software design of the automated focus system is a closed loopsoftware controlled system that utilizes the focus curve as shown inFIG. 14 as a virtual feedback. The design proposal for the focusalgorithm created by the author is as follows:

move slide to preset near focus distance (greater than nominal focaldistance);

capture image and process line profiles;

increment slide toward imager by 25 steps (microns);

capture image and process line profiles;

repeat steps 3 and 4 one or more times;

calculate present focal distance according to pre-calculated focalcurve;

move to nominal focal distance according to pre-calculated focal curve;and

capture image and verify correct focal distance with line profile andhistogram.

Since a single line profile may allow for failure in the above process,many line profiles are preferably examined and averaged in order toeffectively focus a lens to an imager in a production setting. However,the single line profile used in experimentation exhibits thepredictability and repeatability of the focal length curve.

Thus, the software needed to control the auto-focus system shouldaccomplish three things: (1) control the imager; (2) calculate imagedata; and (3) control the slide table for adjustment. In order tocontrol the imager, the digital video signal from the imager may becoming in through USB, and the software may capture individual framesfor calculation upon command. The software also may be capable ofreading and writing exposure and gain values for image capture.

The GUI must be able to interactively place and store multiple lineROI's in order to take measurements across the image. Line profiles thatcorrelate with the line ROI's are calculated to find the measure offocus at that specific position. The derivative of each line profile istaken in order to find the slope of the line profile. After thesecalculations are complete for one image, the peak slopes from each lineprofile will be averaged together. This number will be compared to astored table that the program will be able to access in order to findthe approximate distance (number of steps) away from nominal focus.After the nominal focus has been reached by means of line profile, theGUI is able to calculate histograms from multiple rectangular ROI's.These histograms may reveal the percentage of data between the two peaksof the histograms, and the control may average that percentage to give avalidation to the line profile. The software and control are furtherable to either virtually or physically interface to the slide controllerpackage in order to input distances and command operations to the slidecontroller.

After completing several iterations of the focus experiment, severalconclusions were made. The target design should have a white object on ablack background with angled edges by which line profiles and histogramsmay discern a sharp focused edge. The histogram method of detectingfocus was adequate for detecting focus. However, this method requiredthe motion control to step through many increments of focal length untilthe histogram criteria reached acceptable limits. Although this methodwould be adequate and relatively simple to implement, the line profilemethod revealed a more calculable and immediate pattern of focus.

The line profile method of measuring focus is readily chartable andpredictable across the focal distance range. However, although theboundary region between a white and black target may be readilyexamined, whereby the sharpness of the target is only measured at thatpoint in the target image, more line profiles may be needed to beperformed across the image for real-world or non black and white targetapplications.

Thus, the mathematical algorithm and the curve data methodologydiscussed above may be implemented as a focus algorithm for present andfuture forward facing imager systems (and optionally rearward facingimager systems and/or sideward facing imager systems and the like).Although each imager and lens combination will have its own focus curvedata, the initial data collection will be a minimal component to thesetup procedure. Preferably, the focus can and should be attained bygoing directly to a calculated focal distance processed by initialout-of-focus images captured by the imager. By using this procedure,attaining focus in a production scenario can be greatly hastened.

Real lenses do not typically focus all rays perfectly due to sphericalor other aberrations, diffraction effects from wave optics and thefinite aperture of the lens, resulting in an unfocused image with acircle of confusion CL, which is an essentially constant value dependenton lens quality and independent of the distance of the object or theimage from the optical center of the lens. The combined effects resultin a total circle of confusion CT for images received by the imagesensor. Further, the magnification M of the lens is defined as the ratioof the image dimension LI to the object dimension LO. Thus, M=LI/LO.

High volume component manufacturing and assembly processes used in theproduction of optical systems at low cost typically result in part topart variations in their optical characteristics. Additionally,dimensional tolerances are associated with the manufacture of thehousing assembly components, with the placement of the imaging array diein its package, and with the placement of the imaging array on theprinted circuit board assembly.

Forward facing image capture and signal processing components, such asincorporated in the described AHB control system, may be used to obtaininformation regarding the location, movement and other characteristicsof many objects of relevance to the driving task or operation of thevehicle within the image sensor's field of view, in order to provideadditional features and functions, such as, but not limited to, trafficlane detection and lane departure warning, traffic sign recognition,traffic light status detection, fog detection, rain sensing, and/or tosupplement or complement the use of other sensors or sensingtechnologies in the provision of other features and functions such as,but not limited to, adaptive cruise control, pre-crash sensing,pedestrian detection, etc., thus increasing the utility and value of theAHB control system and reducing the cost and space requirementsassociated with providing each of the features and functions asindependent stand-alone systems.

In order to provide optimum detection and characterization of the widerange of objects of relevance or interest in support of the above listedfeatures and functions, amongst others, under a wide range of lightingconditions, it is necessary to consider the requirements of eachdetection task or group of similar detection tasks.

Typical fixed beam forward lighting systems offer two beam patterns, lowand high, with low beam preferably providing the maximum forward andlateral road illumination without causing direct glare to other oncomingor leading vehicle operators such that it may be used in all drivingconditions, and high beam preferably providing the maximum forwardillumination range with reduced lateral coverage to provide improvedforward visibility during night driving when other road users are notpresent within the extended illuminated region, that is, the region inwhich they would be subject to glare from the vehicle's high beamheadlamps.

Optionally, AHB control systems may incorporate a low speed thresholdbelow which high beam selection is inhibited, in order to avoidactivation of high beams when unnecessary, such as when driving at aspeed which is safe given the forward visibility provided by the lowbeam lighting, or when undesirable, such as when driving on city roads.

There are, however, circumstances above this low speed threshold inwhich it is desirable to maintain, or switch to, a low beam state, evenin the absence of other road users in the high beam illumination region.One such circumstance occurs when the vehicle is driven round a bendwith a short radius of curvature. In this situation the value of thelong range illumination resulting from the use of high beams is reducedsince it is not aligned with the vehicle trajectory and typicallyilluminates off road regions. However, the wider short range beampattern resulting from the use of low beams can provide increasedillumination along the left or right hand curving vehicle trajectory.

Thus, an aspect of the present invention is to improve existing AHBcontrol systems by inhibiting high beam selection when improved relevantroad illumination may be provided by the use of low beam headlights, andin particular when the radius of curvature of the current, orinstantaneous, vehicle trajectory falls below a predetermined thresholdvalue.

The threshold value is ideally determined based on the specific high andlow beam patterns generated by the lighting equipment installed on thevehicle. Additionally, since headlight beam patterns are typicallyasymmetric, and since the distance to the edge of the road is differentwhen driving round a left or right hand curve, the left and right handvehicle trajectory radius of curvature threshold values may bedifferent.

The current or instantaneous vehicle trajectory radius of curvature maybe obtained or derived from several sources, including, but not limitedto steering wheel angular position. The correlation between the vehicletrajectory radius of curvature and steering wheel angular position maybe readily established with knowledge of the vehicle mechanicalconfiguration. Thus, steering wheel angular position thresholds whichare substantially equivalent to vehicle trajectory radius of curvaturethresholds may be derived. Typically, the current, or instantaneous,angular position of the vehicle steering wheel is measured by a rotaryencoder, or equivalent sensing device, and is made available to othervehicle control systems either directly or via a vehicle communicationbus such as a CAN or the like. By accessing this signal or vehicle busmessage, and comparing it to a predetermined threshold, high beamactivation may be inhibited to achieve the previously describedbenefits.

If the vehicle is driven round a long steady curve with a radius ofcurvature which corresponds to the steering wheel angular threshold, itis possible that the instantaneous steering wheel angular value willoscillate about the angular threshold, resulting in a potentiallyannoying or inappropriate oscillation between high and low beam states.Thus, the AHB control system may incorporate a time based filter, whichmay be adaptive, and which may be non-symmetrical, to regulate whatmight otherwise be frequent annoying or inappropriate switching betweenthe low and high beam states. Depending on the characteristics of thetime based filtering system, it may be beneficial to incorporatehysteresis in the angular threshold values, such that the values forleft and right increasing steering wheel angles are greater than thevalues for left and right decreasing steering wheel angles.

Automatic image based high beam control systems (such as described inU.S. Pat. No. 6,097,023, which is hereby incorporated herein byreference in its entirety), in which an image of the scene forward ofthe vehicle is focused by an optical system, may have a horizontal fieldof view equal to, but not limited to, approximately +/−22.5 degreesabout the imaging system centerline. The image may be focused or imagedonto a rectangular array image capture device such as, but not limitedto, a 640×480 CMOS color imager, which captures image data and providessequential frames of data indicative of the light energy reflected oremitted by objects in the region subtended by each element of the array.The image capture rate may be at a rate in the range of about 5 to 120times per second or more, with processing being performed on the data todetermine the presence, location and characteristics of objects withinthe monitored scene and to determine characteristics of the monitoredscene, such as general illumination level, and to utilize severaldefined regions of the monitored scene for several different purposes.For example, the region of the scene which generally corresponds to theregion of influence of the vehicle high beam pattern, may be used todetermine the need to inhibit high beam activation if other road usersare detected within that region. The regions to the left and right ofthe first region may be used to anticipate the upcoming entry of otherroad users into the first region in order to facilitate a rapid andappropriate response upon entry or just prior to entry of the firstregion. The upper central region of the monitored scene may be used todetermine ambient lighting conditions such that a first threshold may beestablished below which low beam headlights are activated, and a secondthreshold may be established above which high beam activation may beinhibited, while the lower horizontal portion of the ambient lightingcondition detection region may be used to detect urban lightingconditions or the like. Other processing of the captured image data maybe implemented depending on the particular application of the imagesensor and processor, while remaining within the spirit and scope of thepresent invention.

While the segmentation of the monitored scene into fixed regions, suchas described above, provides many benefits and efficiencies to the imageprocessing routines used to characterize vehicular light sources,ambient lighting conditions, and non-vehicular light sources etc., theyonly provide optimal performance when they are appropriately alignedwith the monitored scene, such as when driving on a flat straight road.Much of the typical driving experience, however, is on curved andundulating roads. It is, therefore, desirable to have dynamicsegmentation of the monitored scene such that the various regionsemployed align appropriately according to the upcoming road topology andgeometry.

An additional aspect of the present invention is to improve theperformance of AHB control systems by providing a dynamic segmentationof the monitored scene.

When driving on a curved road, it is beneficial to extend the regionused to detect and monitor vehicular light sources in the direction ofroad curvature in order to provide a sufficiently early detection ofother road users and thus the inhibition of high beams. This region maybe extended in accordance with the vehicle trajectory radius ofcurvature as determined by the steering wheel angle or other means aspreviously described. Additionally, the upcoming road condition may beanticipated by other means, such as vehicle pitch as may be monitored byan accelerometer, combination of accelerometers or other means, such asby detection of vehicle roll, visible horizon tilt and/or yaw detectionand/or in response to a GPS output or the like.

An additional aspect of the present invention is to improve theperformance of AHB control systems, when used in conjunction withadaptive forward lighting (AFL) systems, by actively changing the regionof high beam inhibit in response to the vehicle trajectory radius ofcurvature, in order that it corresponds to the current region ofinfluence of the high beam pattern.

Typical AFL systems are responsive to the vehicle trajectory radius ofcurvature and provide improved road surface illumination when driving oncurved roads by mechanically, or otherwise, adjusting the beam directionor providing supplementary illumination in the direction of the curve.While this provides a solution to the problem addressed above for fixedbeam systems, it introduces a shortcoming for a typical fixed beam highbeam control system when used to control high beam selection in an AFLsystem.

While the detection of leading and on-coming/approaching vehicles occursacross a wide field of view, the inhibition of high beam selectionoccurs in a narrower fixed region which corresponds to the region ofinfluence of the fixed high beam pattern. When driving around a curvewith an AFL system, the region of influence of the adaptive high beampattern is extended in the direction of the curve, thus reducing theeffective response time to a vehicle entering the region of high beaminhibit from the direction of the road curvature. It is, thereforeadvantageous to modify the region of high beam inhibit in correspondencewith the modified high beam pattern.

While this may be accomplished through image processing and sceneanalysis, it is preferable, in order to minimize the complexity, andtherefore to minimize the cost of implementation, of the imageprocessing algorithms employed, to use a signal indicative of thevehicle trajectory radius of curvature or the AFL system beam directioncontrol signal. As previously described, the steering wheel angle may bemost conveniently used since it correlates to the vehicle trajectoryradius of curvature and is commonly available from the vehicle data bus.The region of high beam inhibit may be adjusted in a continuous fashionin correspondence with the instantaneous high beam direction, or it maybe adjusted in one or more steps according to one or more steering wheelangle threshold values.

An additional aspect of the present invention is to improve theperformance of existing AHB control systems by improving thecharacterization of non-vehicular light sources when driving on curvedroads.

In order to enhance AHB control system performance, it is desirable toprovide accurate detection and characterization of other vehicular roadusers in order to assure the appropriate inhibition of high beam use.Additionally, all other light sources within the monitored scene may becharacterized as non-vehicular in order to enhance or maximize forwardvision by enabling high beams whenever appropriate and also to avoid theannoyance caused to the user by inappropriate returns to low beams dueto the false characterization of non-vehicular light sources asvehicular sources.

Spatial, spectral and temporal techniques are typically used to aid inthe appropriate characterization of light sources. It is, however,particularly challenging to correctly characterize light sources whendriving round road curves which are provided with reflective signs toindicate road curvature. To achieve the greatest visibility of thesesigns or reflectors, they are typically located and oriented to providethe maximum possible reflection of light from the host vehicleheadlights, that is, at a height above ground level which is similar tothat of typical vehicle lights and oriented such that they reflect lightfrom the headlight beams directly back towards the host vehicle as itprogresses around the bend. Thus, the spectral and geometriccharacteristics and locations of these signs or reflectors may besimilar to that of other vehicles traveling along the curve or bend inthe road.

An additional aspect of the present invention is to improve theperformance of existing AHB control systems by providing an automaticrepeating alignment of the sensor to the vehicle centerline and thehorizontal plane such that the various regions of interest within thescene monitored by the sensor are optimally maintained regardless ofvehicle and high beam control system module geometric manufacturing andassembly tolerances, and other sources of misalignment such as vehicleattitude variations due to a wide range of possible vehicle loadingconditions.

In order to take advantage of the environmental protection offered bythe vehicle cabin, the frequently cleaned optically clear path offeredby the vehicle windshield (which is cleaned or wiped by the windshieldwipers when the wipers are activated), and the relatively high vantagepoint offered at the upper region or top of the windshield, AHB controlsystems are preferably mounted centrally on the upper inside surface ofthe front windshield of a vehicle and with a forward field of viewthrough the region cleaned or wiped by the windshield wipers.

Typical vehicle body structures, windshields and assembly systems eachcontribute to the geometric tolerance associated with the surface towhich the AHB control system module is attached. The module also hassome degree of geometric tolerance associated with its components andassembly methods. It is not unusual to encounter a total stack up oftolerances which result in a potential vertical and horizontalmisalignment of +/−2 degrees from the theoretically ideal condition.This is a significant value and may result in errors in determining lanewidths and object sizes and distances and the like.

It is known to provide a mechanical adjustment means to allow for thecorrection of this misalignment at the installation of the AHB controlsystem to the vehicle. This is, however, often undesirable since itoften is expensive to apply manual labor to the alignment of componentson each vehicle equipped with an AHB control system on the vehicleassembly line. It is additionally undesirable since the alignmentprocedure is subject to operator error.

Also, during the lifetime of the vehicle the windshield may be damagedand require replacement. In such an event it would be necessary, andlikely at an unacceptable cost, to provide the alignment techniques,tools and equipment to every service operation that may be required toreplace a windshield and remount the AHB control system module in orderto return the vehicle to its original performance level.

Additionally, in normal use, a typical vehicle experiences manydifferent loading conditions which cause it to adopt a wide range ofpitch and roll attitudes, causing an AHB control system which isattached to the vehicle to view the forward scene from perspectivesdifferent from the ideal, or initially considered design condition,potentially resulting in different headlight actuation decisions thancontemplated by the original system specification.

Thus, it is beneficial for an AHB control system to include a featurewhich automatically compensates for an initial misalignment conditionand additionally is capable of correcting for temporary vehicleconditions and re-installation misalignments which may occur during theuse of the vehicle.

In order to achieve optimum performance of the AHB control system, it isdesirable to determine which of the array elements of the image capturedevice fall into each of the defined regions. Since the regions aredefined relative to the forward scene, it is desirable to determine aparticular point within the forward scene and to relate that point to aparticular array element of the image capture device.

The particular point in the forward scene may be defined as a particulardistant point which lies on the forward extended vehicle centerline onthe horizontal plane which passes through the center of the opticalsystem associated with the image capture device. When driving on asubstantially flat and substantially straight road, the distant pointmay be the point within the forward scene at which the headlights of anoncoming vehicle or the tail lamps of a slower leading vehicle are firstdetected. As the distance between the host and target vehiclesdecreases, the image of the target vehicle expands within the imagedscene, towards the left if traveling in a leftward lane, centrally if inthe same lane, and towards the right if traveling in a rightward lane.Thus the described distant point may be called the focus of expansion orFOE.

In order to determine the imaging array element or pixel which subtendsthe FOE in the as assembled and as loaded vehicle, it is necessary toidentify the array element which first detects a new light source, whichhas the potential to be a vehicular source, within that region of themonitored scene which could potentially contain the FOE, to continue totrack the light source as it expands in the image as the distancebetween the detected source and the host vehicle decreases until it isconfirmed that the source is vehicular, and to monitor the host vehicletrajectory until it reaches the point in the road where the new lightsource would have been initially detected in order to confirm that theroad traveled for the duration of the monitoring period wassubstantially flat and substantially straight. If it is determined thatthe point or light source is a vehicle and the host vehicle andapproaching vehicle are traveling along a substantially flat andsubstantially straight road, the location of the initial distant pointor FOE may be compared to an expected location and the axis of theimaging system may be adjusted accordingly so that the imaging system isdirected at the desired or appropriate or optimal angle relative to thevehicle. Optionally, the imaging system may be adjusted in response to adetection of lane markers along a straight and/or flat road, and/orpitch information from a bus or accelerometer and/or roll informationfrom an accelerometer or bus information. Optionally, the system mayonly monitor for new light sources when the steering wheel angle orsteering angle (SA) is approximately 0 degrees, such as when thesteering angle is about 0 degrees +\−0.1 degrees or other thresholdangle. Thus, adjustment and/or alignment of the image sensor may occurby tracking movement of light sources through the images when thevehicle is traveling substantially straight, so that the control maycompare the tracked light sources to expected locations and pathsthrough the captured images as the vehicle moves along the substantiallystraight path and may adjust the field of view or viewing angle of theimage sensor accordingly.

An additional aspect of the present invention is to improve AHB controlsystems by providing a detection of left and right hand road systems andan automatic configuration to assure appropriate left or right handoperation. AHB control systems are often installed on both left andright hand drive vehicles and may be configured differently for use onleft and right hand drive road systems, preferably having an asymmetricresponse to activity within the monitored scene. It is possible toconfigure the system to operate on either a left or right hand drivevehicle and to supply the system to the vehicle assembly plant forinstallation on a corresponding either left or right hand drive vehicle.In such cases it is desirable to identify the AHB control system modulewith a particular part number in order to assure the installation of thecorrect configuration, which results in part number proliferation andthe potential for operator error, either at the module manufacturinglocation where the wrong label may be attached to the product, or at thevehicle assembly plant, particularly if left and right hand drivevehicles are built on the same assembly line, where the wrong part maybe selected for installation.

In order to reduce part number proliferation, it is possible to providea switch on the AHB control system module in order to configure it foroperation on a left or right hand drive vehicle. This solution, however,is also subject to operator error and may result in incorrect andinappropriate control of the vehicle high beams during nighttimedriving. Additionally, during the normal use of a right hand drivevehicle, it may be driven on a left hand drive road system for a periodof time before returning to a right hand drive road system and viceversa, such as when taking a vehicle by ferry or Channel tunnel from theUnited Kingdom to mainland Europe for vacation or in the course ofbusiness. Again it is possible to provide a switch to allow the vehicleoperator to configure the system appropriately for the country of use,however, this is inconvenient and may result in inappropriate high beamactivation in the event that the operator forgets to, or is unaware ofthe need to switch to the alternate configuration, or is unaware of theavailability of a reconfiguration switch. Thus, there is a need toprovide an automatic configuration of AHB control systems such that theyanalyze the monitored scene, recognize a left or right hand drive roadsystem and self-configure accordingly.

The system may track the light sources and adjust the image sensor onlywhen the steering angle is within a threshold value of straight orsubstantially straight, in order to avoid misinterpretation of sourcelocations. Also, the system may take into account the environment atwhich the vehicle is traveling, and may not track and adjust when thevehicle is traveling in high lighting environments, such as cities andthe like, and may function when there are limited other light sources inthe forward field of view. The system may also take into account thespeed of the vehicle and thus the speed of the light moving through thecaptured images.

Optionally, when the vehicle is being passed on tight curves or thelike, the control may determine when to adjust the headlamps of thevehicle in response to the location and departure of the passingvehicle's taillights within the field of view. For example, the controlmay take into account situations when the forward vehicle departs thefield of view while the steering angle of the subject vehicle remainsrelatively constant, and may adjust the headlamps accordingly. Suchtracking may also provide an indication that the road continues to curveahead of the subject vehicle, and may provide information useful inconjunction with an adaptive cruise control (ACC) system and/or a lanedeparture warning (LDW) or the like.

Adaptive Front Lighting vehicles can illuminate curved road areas andvehicles that previously were not illuminated very well. The AHBCalgorithm could, at significant expense and speed penalties, decide whenthe vehicle was on a curve and change its operation. If the AHBC systemcould use steering wheel angle (SWA) from the automobile bus, it couldreact significantly faster, with fewer mistakes, without the calculationpenalties of internal SWA calculation.

We have done several studies on how the steering wheel angle willimprove AHBC functionality when used with AFLS. For example, 14 vehiclesin 7 video clips which had both AFLS cars and standard cars werestudied. These clips showed vehicles traveling on a curve and wereexamined to determine how to better detect these vehicles. The region ofinterest was extended manually in the direction of the curved travel.The SWA was not used during such examination and evaluation, but it isenvisioned that the use of steering wheel angle would allow theseresults to be done automatically. Based on such evaluations, the optimumsize and location of the region of interest (ROI) may be found. The ROIis the vehicle processing region. Surprisingly (and as shown in FIG. 9),the optimum ROI change was not a linear function of the SWA size. It wasjust a simple rule to extend the ROI one amount in the curve direction.During a sharp turn of the vehicle, the vehicle is seen for a short timeand for gentle curves the vehicle is seen for a longer time. Resultsvary with the orientation of the target vehicle with respect to the hostvehicle. This is related to the beam intensity pattern.

The smaller amount of gained low beam time on a sharp curve is not to bebelittled. The total time that the vehicle was visible in the imagingsystem on sharp curves averaged around 3-4 seconds. The addition of 0.6seconds of low beam time is significant since these vehicle detectionsusually only had a couple seconds of low beam, so the added time is asignificant benefit. For the gentle curves the vehicles were visible inthe scene for longer, and were detected in low beam for about 1.6seconds more, thus the added time was significant.

In the future when more target vehicles have adaptive front lighting,this effect may not be so static. Then the ROI may need to be changed asa function of the steering wheel angle. The desired approach was toextend the ROI 5 or 6 degrees in the direction of the curve denoted bythe steering wheel angle. With no or small SWA, the ROI is unchanged.This approach is enough to provide significant benefit for the AHBCvehicle with AFLS. The AFLS system does point the headlights in thedirection of the curve and this use of SWA will allow the quickerdetection of the target vehicle so that the effect of the AFLS isminimized for other drivers. The other vehicles will not get as muchunexpected glare at unexpected angles on a curve, because they will bedetected sooner by the host AHBC vehicle.

Optionally, the SWA may be used to filter out the false alarm targetsfrom reflectors and house and yard lights on curves. When the vehicle isdriven along the road, the system does not know how the road curvesahead and if it did, such as through SWA, the system could better filterout such false targets. This is particularly evident when the falsetarget is straight ahead, while the road curves. In such cases, thefalse target is in the same position as a real vehicle. With the use ofthe steering wheel angle, this false alarm can be minimized, and it isestimated that at least about a third of these kinds of false alarmscould be eliminated. These also are the most resistant false alarmssince they look the most like real car lights.

Finally, the use of SWA could allow us to better filter out thenon-straight roads that should be ignored to adapt the focus ofexpansion. The system can accumulate the focus of expansion data when itdetects the lane markers, and may only accumulate when the FOE is closeenough to the manufacturing value. The system could better filter outthese curved road times and should allow the system to get a better,quicker, measure of the real FOE for a given key cycle.

Therefore, the use of SWA will allow quicker use of low beams on curveswhere the AFLS system will otherwise glare opposing vehicles more thanthe non-AFLS vehicle. The detection time, when low beam is on, maypreferably increase by about 30 percent or more. The use of SWA willalso allow better filtering out of noise sources which falsely triggerlow beam, and it will more quickly provide adaptive focus of expansionin general driving.

The imaging sensor for the headlamp control of the present invention maycomprise any suitable sensor, and may utilize various imaging sensors orimaging array sensors or cameras or the like, such as a CMOS imagingarray sensor, a CCD sensor or other sensors or the like, such as thetypes described in U.S. Pat. Nos. 6,946,978; 7,004,606; 5,550,677;5,760,962; 6,097,023; 5,796,094 and/or 5,715,093; and/or U.S. patentapplications, Ser. No. 09/441,341, filed Nov. 16, 1999, now U.S. Pat.No. 7,339,149; and/or Ser. No. 11/105,757, filed Apr. 14, 2005, now U.S.Pat. No. 7,526,103, and/or PCT Application No. PCT/US2003/036177 filedNov. 14, 2003, published Jun. 3, 2004 as PCT Publication No. WO2004/047421, which are all hereby incorporated herein by reference intheir entireties.

Optionally, the imaging sensor may be suitable for use in connectionwith other vehicle imaging systems, such as, for example, a blind spotdetection system, where a blind spot indicator may be operable toprovide an indication to the driver of the host vehicle that an objector other vehicle has been detected in the lane or area adjacent to theside of the host vehicle. In such a blind spot detector/indicatorsystem, the blind spot detection system may include an imaging sensor orsensors, or ultrasonic sensor or sensors, or sonar sensor or sensors orthe like. For example, the blind spot detection system may utilizeaspects of the blind spot detection and/or imaging systems described inU.S. Pat. Nos. 7,038,577; 6,882,287; 6,198,409; 5,929,786 and/or5,786,772, and/or U.S. patent applications, Ser. No. 11/315,675, filedDec. 22, 2005, now U.S. Pat. No. 7,720,580; and/or Ser. No. 11/239,980,filed Sep. 30, 2005, now U.S. Pat. No. 7,881,496, and/or U.S.provisional applications, Ser. No. 60/696,953, filed Jul. 6, 2006; Ser.No. 60/628,709, filed Nov. 17, 2004; Ser. No. 60/614,644, filed Sep. 30,2004; and/or Ser. No. 60/618,686, filed Oct. 14, 2004, and/or of thereverse or backup aid systems, such as the rearwardly directed vehiclevision systems described in U.S. Pat. Nos. 5,550,677; 5,760,962;5,670,935; 6,201,642; 6,396,397; 6,498,620; 6,717,610; 6,757,109 and/or7,005,974, and/or of the rain sensors described in U.S. Pat. Nos.6,250,148 and 6,341,523, and/or of other imaging systems, such as thetypes described in U.S. Pat. Nos. 6,353,392 and 6,313,454, and U.S.patent application, Ser. No. 10/422,512, filed Apr. 24, 2003, now U.S.Pat. No. 7,123,168, with all of the above referenced U.S. patents,patent applications and provisional applications and PCT applicationsbeing commonly assigned and being hereby incorporated herein byreference.

Optionally, the mirror assembly and/or accessory module or windshieldelectronics module may include one or more displays, such as fordisplaying the captured images or video images captured by the imagingsensor or sensors of the vehicle, such as the displays of the typesdisclosed in U.S. Pat. Nos. 7,004,593; 5,530,240 and/or 6,329,925, whichare hereby incorporated herein by reference, and/or display-on-demand ortransflective type displays, such as the types disclosed in U.S. Pat.Nos. 6,690,268; 5,668,663 and/or 5,724,187, and/or in U.S. patentapplications, Ser. No. 10/054,633, filed Jan. 22, 2002, now U.S. Pat.No. 7,195,381; Ser. No. 11/021,065, filed Dec. 23, 2004, now U.S. Pat.No. 7,255,451; Ser. No. 10/528,269, filed Mar. 17, 2005, now U.S. Pat.No. 7,274,501; Ser. No. 10/533,762, filed May 4, 2005, now U.S. Pat. No.7,184,190; Ser. No. 10/538,724, filed Jun. 13, 2005 and published Mar.9, 2006 as U.S. Publication No. US-2006-0050018; Ser. No. 11/226,628,filed Sep. 14, 2005 and published Mar. 9, 2006 as U.S. Publication No.US-2006-0061008; Ser. No. 10/993,302, filed Nov. 19, 2004, now U.S. Pat.No. 7,338,177; and/or Ser. No. 11/284,543, filed Nov. 22, 2005, now U.S.Pat. No. 7,370,983, and/or PCT Application No. PCT/US03/29776, filedSep. 9, 2003; and/or PCT Application No. PCT/US03/35381, filed Nov. 5,2003, and/or PCT Application No. PCT/US03/40611, filed Dec. 19, 2003,which are all hereby incorporated herein by reference, or may include orincorporate video displays or the like, such as the types described inPCT Application No. PCT/US03/40611, filed Dec. 19, 2003, and/or U.S.patent applications, Ser. No. 10/538,724, filed Jun. 13, 2005 andpublished Mar. 9, 2006 as U.S. Publication No. US-2006-0050018; and/orSer. No. 11/284,543, filed Nov. 22, 2005, now U.S. Pat. No. 7,370,983,and/or U.S. provisional applications, Ser. No. 60/732,245, filed Nov. 1,2005; Ser. No. 60/759,992, filed Jan. 18, 2006; and/or Ser. No.60/836,219, filed Aug. 8, 2006, which are hereby incorporated herein byreference.

The imaging sensor may be incorporated at or in an accessory module orwindshield electronics module (such as described above), or may beincorporated at or in an interior rearview mirror assembly of thevehicle, while remaining within the spirit and scope of the presentinvention. Optionally, the mirror assembly and/or module may support oneor more other accessories or features, such as one or more electrical orelectronic devices or accessories. For example, illumination sources orlights, such as map reading lights or one or more other lights orillumination sources, such as illumination sources of the typesdisclosed in U.S. Pat. Nos. 6,690,268; 5,938,321; 5,813,745; 5,820,245;5,673,994; 5,649,756; 5,178,448; 5,671,996; 4,646,210; 4,733,336;4,807,096; 6,042,253; 6,971,775 and/or 5,669,698, and/or U.S. patentapplications, Ser. No. 10/054,633, filed Jan. 22, 2002, now U.S. Pat.No. 7,195,381; and/or Ser. No. 10/933,842, filed Sep. 3, 2004, now U.S.Pat. No. 7,249,860, which are hereby incorporated herein by reference,may be included in the mirror assembly or module. The illuminationsources and/or the circuit board may be connected to one or more buttonsor inputs for activating and deactivating the illumination sources.Optionally, the mirror assembly or module may also or otherwise includeother accessories, such as microphones, such as analog microphones ordigital microphones or the like, such as microphones of the typesdisclosed in U.S. Pat. Nos. 6,243,003; 6,278,377 and/or 6,420,975,and/or in PCT Application No. PCT/US03/308877, filed Oct. 1, 2003.Optionally, the mirror assembly may also or otherwise include otheraccessories, such as a telematics system, speakers, antennas, includingglobal positioning system (GPS) or cellular phone antennas, such asdisclosed in U.S. Pat. No. 5,971,552, a communication module, such asdisclosed in U.S. Pat. No. 5,798,688, a voice recorder, transmittersand/or receivers, such as for a garage door opener or a vehicle doorunlocking system or the like (such as a remote keyless entry system), adigital network, such as described in U.S. Pat. No. 5,798,575, a memorymirror system, such as disclosed in U.S. Pat. No. 5,796,176, ahands-free phone attachment, a video device for internal cabinsurveillance (such as for sleep detection or driver drowsiness detectionor the like) and/or video telephone function, such as disclosed in U.S.Pat. Nos. 5,760,962 and/or 5,877,897, a remote keyless entry receiver, aseat occupancy detector, a remote starter control, a yaw sensor, aclock, a carbon monoxide detector, status displays, such as displaysthat display a status of a door of the vehicle, a transmission selection(4wd/2wd or traction control (TCS) or the like), an antilock brakingsystem, a road condition (that may warn the driver of icy roadconditions) and/or the like, a trip computer, a tire pressure monitoringsystem (TPMS) receiver (such as described in U.S. Pat. Nos. 6,124,647;6,294,989; 6,445,287; 6,472,979 and/or 6,731,205; and/or U.S. patentapplication Ser. No. 11/232,324, filed Sep. 21, 2005, now U.S. Pat. No.7,423,522, and/or an ONSTAR® system and/or any other accessory orcircuitry or the like (with all of the above-referenced patents and PCTand U.S. patent applications being commonly assigned, and with thedisclosures of the referenced patents and patent applications beinghereby incorporated herein by reference in their entireties).

Optionally, the mirror assembly or module may include one or more userinputs for controlling or activating/deactivating one or more electricalaccessories or devices of or associated with the mirror assembly ormodule or vehicle. The mirror assembly or module may comprise any typeof switches or buttons, such as touch or proximity sensing switches,such as touch or proximity switches of the types described in PCTApplication No. PCT/US03/40611, filed Dec. 19, 2003; and/or U.S. Pat.Nos. 6,001,486; 6,310,611; 6,320,282 and 6,627,918; and/or U.S. patentapplications, Ser. No. 09/817,874, filed Mar. 26, 2001, now U.S. Pat.No. 7,224,324; Ser. No. 10/956,749, filed Oct. 1, 2004, now U.S. Pat.No. 7,446,924; Ser. No. 10/933,842, filed Sep. 3, 2004, now U.S. Pat.No. 7,249,860; Ser. No. 11/021,065, filed Dec. 23, 2004, now U.S. Pat.No. 7,255,451; and/or Ser. No. 11/140,396, filed May 27, 2005, now U.S.Pat. No. 7,360,932, which are hereby incorporated herein by reference,or the inputs may comprise other types of buttons or switches, such asthose described in U.S. patent applications, Ser. No. 11/029,695, filedJan. 5, 2005, now U.S. Pat. No. 7,253,723; and/or Ser. No. 11/451,639,filed Jun. 13, 2006, now U.S. Pat. No. 7,527,403, which are herebyincorporated herein by reference, or such as fabric-made positiondetectors, such as those described in U.S. Pat. Nos. 6,504,531;6,501,465; 6,492,980; 6,452,479; 6,437,258 and 6,369,804, which arehereby incorporated herein by reference. Other types of switches orbuttons or inputs or sensors may be incorporated to provide the desiredfunction, without affecting the scope of the present invention.

Optionally, the user inputs or buttons may comprise user inputs for agarage door opening system, such as a vehicle based garage door openingsystem of the types described in U.S. Pat. Nos. 6,396,408; 6,362,771 and5,798,688, and/or U.S. patent application Ser. No. 10/770,736, filedFeb. 3, 2004, now U.S. Pat. No. 7,023,322; and/or U.S. provisionalapplications, Ser. No. 60/502,806, filed Sep. 12, 2003; and Ser. No.60/444,726, filed Feb. 4, 2003, which are hereby incorporated herein byreference. The user inputs may also or otherwise function to activateand deactivate a display or function or accessory, and/or mayactivate/deactivate and/or commence a calibration of a compass system ofthe mirror assembly and/or vehicle. The compass system may includecompass sensors and circuitry within the mirror assembly or within acompass pod or module at or near or associated with the mirror assembly.Optionally, the user inputs may also or otherwise comprise user inputsfor a telematics system of the vehicle, such as, for example, an ONSTAR®system as found in General Motors vehicles and/or such as described inU.S. Pat. Nos. 4,862,594; 4,937,945; 5,131,154; 5,255,442; 5,632,092;5,798,688; 5,971,552; 5,924,212; 6,243,003; 6,278,377; 6,420,975;6,946,978; 6,477,464; 6,678,614 and/or 7,004,593, and/or U.S. patentapplications, Ser. No. 10/645,762, filed Aug. 20, 2003, now U.S. Pat.No. 7,167,796; and Ser. No. 10/964,512, filed Oct. 13, 2004, now U.S.Pat. No. 7,308,341; and/or PCT Application No. PCT/US03/40611, filedDec. 19, 2003, and/or PCT Application No. PCT/US03/308877, filed Oct. 1,2003, which are all hereby incorporated herein by reference.

Optionally, the accessory module may utilize aspects of other accessorymodules or windshield electronics modules or the like, such as the typesdescribed in U.S. patent applications, Ser. No. 10/958,087, filed Oct.4, 2004, now U.S. Pat. No. 7,188,963; and/or Ser. No. 11/201,661, filedAug. 11, 2005, now U.S. Pat. No. 7,480,149, and/or U.S. Pat. Nos.7,004,593; 6,824,281; 6,690,268; 6,250,148; 6,341,523; 6,593,565;6,428,172; 6,501,387; 6,329,925 and 6,326,613, and/or in PCT ApplicationNo. PCT/US03/40611, filed Dec. 19, 2003, and/or Ireland patentapplications, Ser. No. S2004/0614, filed Sep. 15, 2004; Ser. No.S2004/0838, filed Dec. 14, 2004; and Ser. No. S2004/0840, filed Dec. 15,2004, which are all hereby incorporated herein by reference.

The reflective element of the rearview mirror assembly of the vehiclemay comprise an electro-optic or electrochromic reflective element orcell, such as an electrochromic mirror assembly and electrochromicreflective element utilizing principles disclosed in commonly assignedU.S. Pat. Nos. 6,690,268; 5,140,455; 5,151,816; 6,178,034; 6,154,306;6,002,544; 5,567,360; 5,525,264; 5,610,756; 5,406,414; 5,253,109;5,076,673; 5,073,012; 5,117,346; 5,724,187; 5,668,663; 5,910,854;5,142,407 and/or 4,712,879, and/or U.S. patent applications, Ser. No.10/054,633, filed Jan. 22, 2002, now U.S. Pat. No. 7,195,381; Ser. No.11/021,065, filed Dec. 23, 2004, now U.S. Pat. No. 7,255,451; Ser. No.11/226,628, filed Sep. 14, 2005 and published Mar. 9, 2006 as U.S.Publication No. US-2006-0061008, and/or PCT Application No.PCT/US2006/018567, filed May 15, 2006, which are all hereby incorporatedherein by reference, and/or as disclosed in the following publications:N. R. Lynam, “Electrochromic Automotive Day/Night Mirrors”, SAETechnical Paper Series 870636 (1987); N. R. Lynam, “Smart Windows forAutomobiles”, SAE Technical Paper Series 900419 (1990); N. R. Lynam andA. Agrawal, “Automotive Applications of Chromogenic Materials”, LargeArea Chromogenics: Materials and Devices for Transmittance Control, C.M. Lampert and C. G. Granquist, EDS., Optical Engineering Press, Wash.(1990), which are hereby incorporated by reference herein. Thethicknesses and materials of the coatings on the substrates of theelectrochromic reflective element, such as on the third surface of thereflective element assembly, may be selected to provide a desired coloror tint to the mirror reflective element, such as a blue coloredreflector, such as is known in the art and/or such as described in U.S.Pat. Nos. 5,910,854 and 6,420,036, and in PCT Application No.PCT/US03/29776, filed Sep. 9, 2003, which are all hereby incorporatedherein by reference.

Optionally, use of an elemental semiconductor mirror, such as a siliconmetal mirror, such as disclosed in U.S. Pat. Nos. 6,286,965; 6,196,688;5,535,056; 5,751,489 and 6,065,840, and/or in U.S. patent application,Ser. No. 10/993,302, filed Nov. 19, 2004, now U.S. Pat. No. 7,338,177,which are all hereby incorporated herein by reference, can beadvantageous because such elemental semiconductor mirrors (such as canbe formed by depositing a thin film of silicon) can be greater than 50percent reflecting in the photopic (SAE J964a measured), while beingalso substantially transmitting of light (up to 20 percent or evenmore). Such silicon mirrors also have the advantage of being able to bedeposited onto a flat glass substrate and to be bent into a curved (suchas a convex or aspheric) curvature, which is also advantageous sincemany passenger-side exterior rearview mirrors are bent or curved.

Optionally, the reflective element may include a perimeter metallicband, such as the types described in PCT Application No. PCT/US03/29776,filed Sep. 19, 2003; and/or PCT Application No. PCT/US03/35381, filedNov. 5, 2003; and/or U.S. patent applications, Ser. No. 11/021,065,filed Dec. 23, 2004, now U.S. Pat. No. 7,255,451; and/or Ser. No.11/226,628, filed Sep. 14, 2005 and published Mar. 9, 2006 as U.S.Publication No. US-2006-0061008, which are hereby incorporated herein byreference. Optionally, the reflective element may include indicia formedat and viewable at the reflective element, such as by utilizing aspectsof the reflective elements described in PCT Application No.PCT/US2006/018567, filed May 15, 2006, which are hereby incorporatedherein by reference.

Optionally, the reflective element of the mirror assembly may comprise asingle substrate with a reflective coating at its rear surface, withoutaffecting the scope of the present invention. The mirror assembly thusmay comprise a prismatic mirror assembly or other mirror having a singlesubstrate reflective element, such as a mirror assembly utilizingaspects described in U.S. Pat. Nos. 6,318,870; 6,598,980; 5,327,288;4,948,242; 4,826,289; 4,436,371 and 4,435,042; and PCT Application No.PCT/US04/015424, filed May 18, 2004; and U.S. patent application, Ser.No. 10/933,842, filed Sep. 3, 2004, now U.S. Pat. No. 7,249,860, whichare hereby incorporated herein by reference. Optionally, the reflectiveelement may comprise a conventional prismatic or flat reflective elementor prism, or may comprise a prismatic or flat reflective element of thetypes described in PCT Application No. PCT/US03/29776, filed Sep. 19,2003; U.S. patent applications, Ser. No. 10/709,434, filed May 5, 2004,now U.S. Pat. No. 7,420,756; Ser. No. 10/933,842, filed Sep. 3, 2004,now U.S. Pat. No. 7,249,860; Ser. No. 11/021,065, filed Dec. 23, 2004,now U.S. Pat. No. 7,255,451; and/or Ser. No. 10/993,302, filed Nov. 19,2004, now U.S. Pat. No. 7,338,177, and/or PCT Application No.PCT/US2004/015424, filed May 18, 2004, which are all hereby incorporatedherein by reference, without affecting the scope of the presentinvention.

Changes and modifications to the specifically described embodiments maybe carried out without departing from the principles of the presentinvention, which is intended to be limited by the scope of the appendedclaims, as interpreted in accordance with the principles of patent law.

1. A vehicular forward viewing image capture system, said vehicularforward viewing image capture system comprising: an accessory moduleconfigured for attachment at an in-cabin side of a windshield of avehicle equipped with said vehicular forward viewing image capturesystem; wherein said accessory module comprises an imaging sensor, saidimaging sensor comprising a two-dimensional array of photosensorelements; wherein, with said accessory module attached at the in-cabinside of the windshield of the equipped vehicle, said imaging sensor hasa field of view through the windshield forward of the equipped vehicle;a control, said control comprising a digital processor for processingimage data captured by said imaging sensor; wherein, with said accessorymodule attached at the in-cabin side of the windshield of the equippedvehicle, and while the equipped vehicle is traveling along a road, saidcontrol processes captured image data to determine (i) presence of anobject of interest in the forward field of view of said imaging sensorand (ii) location of the object of interest in the forward field of viewof said imaging sensor; wherein said control receives vehicle data via avehicle communication bus; and wherein, with said accessory moduleattached at the in-cabin side of the windshield of the equipped vehicle,and responsive to the processing of captured image data and responsiveto the received vehicle data, said control at least in part provides atleast one selected from the group consisting of (a) traffic signrecognition, (b) traffic light status detection, (c) adaptive cruisecontrol and (d) pedestrian detection.
 2. The vehicular forward viewingimage capture system of claim 1, wherein the received vehicle data atleast comprises a speed signal indicative of speed of the equippedvehicle.
 3. The vehicular forward viewing image capture system of claim2, wherein an output of said control when the speed signal is indicativeof the speed of the equipped vehicle being above a threshold speed levelis different than the output of said control when the speed signal isindicative of the speed of the equipped vehicle being below a thresholdspeed level.
 4. The vehicular forward viewing image capture system ofclaim 1, wherein said vehicle communication bus comprises a CAN vehiclecommunication bus.
 5. The vehicular forward viewing image capture systemof claim 1, wherein captured image data is processed at said control todetermine a characteristic of the object of interest present in theforward field of view of said imaging sensor.
 6. The vehicular forwardviewing image capture system of claim 1, wherein multiple frames ofcaptured image data are processed at said control in determining thelocation of the object of interest present in the forward field of viewof said imaging sensor.
 7. The vehicular forward viewing image capturesystem of claim 1, wherein multiple frames of captured image data areprocessed at said control to determine movement of the object ofinterest present in the forward field of view of said imaging sensor. 8.The vehicular forward viewing image capture system of claim 1, wherein,with said accessory module attached at the in-cabin side of thewindshield of the equipped vehicle, captured image data is processed atsaid control to determine a general illumination level at the equippedvehicle in the forward field of view of said imaging sensor.
 9. Thevehicular forward viewing image capture system of claim 1, wherein, withsaid accessory module attached at the in-cabin side of the windshield ofthe equipped vehicle, captured image data is processed at said controlto determine a road condition of the road ahead of the equipped vehicle.10. The vehicular forward viewing image capture system of claim 1,wherein, with said accessory module attached at the in-cabin side of thewindshield of the equipped vehicle, captured image data is processed atsaid control to determine an incline of the road ahead of the equippedvehicle.
 11. The vehicular forward viewing image capture system of claim1, wherein, with said accessory module attached at the in-cabin side ofthe windshield of the equipped vehicle, and responsive to processing ofcaptured image data, said control determines presence of other roadusers in a region of influence of a vehicle headlamp of the equippedvehicle, and wherein said control is operable to inhibit adjustment of abeam pattern of the vehicle headlamp of the equipped vehicle if otherroad users are detected within the region of influence of the vehicleheadlamp of the equipped vehicle.
 12. The vehicular forward viewingimage capture system of claim 1, wherein said vehicular forward viewingimage capture system automatically compensates for misalignment of saidimaging sensor.
 13. The vehicular forward viewing image capture systemof claim 12, wherein said vehicular forward viewing image capture systemdetermines misalignment of said imaging sensor responsive at least inpart to a focus of expansion ahead of the vehicle.
 14. The vehicularforward viewing image capture system of claim 13, wherein said vehicularforward viewing image capture system determines misalignment of saidimaging sensor responsive to determination of location and movement ofanother vehicle relative to the focus of expansion as the equippedvehicle travels along a straight section of the road.
 15. The vehicularforward viewing image capture system of claim 13, wherein said vehicularforward viewing image capture system determines misalignment of saidimaging sensor responsive to tracking movement of light sources throughmultiple frames of captured image data when the equipped vehicle travelsalong a straight section of the road.
 16. The vehicular forward viewingimage capture system of claim 1, wherein the received vehicle datacomprises (i) vehicle speed data and (ii) vehicle trajectory data. 17.The vehicular forward viewing image capture system of claim 1, whereinthe received vehicle data comprises vehicle GPS data.
 18. The vehicularforward viewing image capture system of claim 1, wherein the receivedvehicle data comprises vehicle pitch data.
 19. The vehicular forwardviewing image capture system of claim 1, wherein the received vehicledata comprises vehicle yaw data.
 20. The vehicular forward viewing imagecapture system of claim 1, wherein, with said accessory module attachedat the in-cabin side of the windshield of the equipped vehicle, saidimaging sensor views through a portion of the windshield that is sweptby a windshield wiper of the equipped vehicle.
 21. The vehicular forwardviewing image capture system of claim 1, wherein said accessory modulecomprises said control and an electrical connector for electricallyconnecting to a vehicle wiring system when said accessory module isattached at the in-cabin side of the windshield of the equipped vehicle.22. The vehicular forward viewing image capture system of claim 1,wherein said accessory module is configured to removably attach at anattachment plate that is fixedly attached at the in-cabin side of thewindshield of the equipped vehicle.
 23. The vehicular forward viewingimage capture system of claim 22, wherein, with said accessory moduleremovably attached at the attachment plate that is fixedly attached atthe in-cabin side of the windshield of the equipped vehicle, theprincipal viewing axis of said imaging sensor is parallel to theprincipal central axis of the equipped vehicle.
 24. The vehicularforward viewing image capture system of claim 1, wherein said control atleast in part provides at least one selected from the group consistingof (a) traffic sign recognition, (b) traffic light status detection, (c)adaptive cruise control and (d) pedestrian detection responsive toprocessing of multiple frames of captured image data.
 25. The vehicularforward viewing image capture system of claim 24, wherein the imagingsensor captures multiple frames of image data at an image capture rateof greater than or equal to five frames per second and less than orequal to 120 frames per second.
 26. A vehicular forward viewing imagecapture system, said vehicular forward viewing image capture systemcomprising: an accessory module configured for attachment at an in-cabinside of a windshield of a vehicle equipped with said vehicular forwardviewing image capture system; wherein said accessory module comprises animaging sensor, said imaging sensor comprising a two-dimensional arrayof photosensor elements; wherein, with said accessory module attached atthe in-cabin side of the windshield of the equipped vehicle, saidimaging sensor has a field of view through the windshield forward of theequipped vehicle; wherein, with said accessory module attached at thein-cabin side of the windshield of the equipped vehicle, said imagingsensor views through a portion of the windshield that is swept by awindshield wiper of the equipped vehicle; a control, said controlcomprising a digital processor for processing multiple frames of imagedata captured by said imaging sensor; wherein, with said accessorymodule attached at the in-cabin side of the windshield of the equippedvehicle, and while the equipped vehicle is traveling along a road, saidcontrol processes multiple frames of captured image data to determine(i) presence of an object of interest in the forward field of view ofsaid imaging sensor, (ii) location of the object of interest in theforward field of view of said imaging sensor and (iii) movement of theobject of interest present in the forward field of view of said imagingsensor; wherein said control receives vehicle data via a vehiclecommunication bus; and wherein, with said accessory module attached atthe in-cabin side of the windshield of the equipped vehicle, andresponsive to the processing of multiple frames of captured image dataand responsive to the received vehicle data, said control at least inpart provides at least one selected from the group consisting of (a)traffic sign recognition, (b) traffic light status detection, (c)adaptive cruise control and (d) pedestrian detection.
 27. The vehicularforward viewing image capture system of claim 26, wherein the receivedvehicle data at least comprises a speed signal indicative of speed ofthe equipped vehicle.
 28. The vehicular forward viewing image capturesystem of claim 27, wherein an output of said control when the speedsignal is indicative of the speed of the equipped vehicle being above athreshold speed level is different than the output of said control whenthe speed signal is indicative of the speed of the equipped vehiclebeing below a threshold speed level.
 29. The vehicular forward viewingimage capture system of claim 26, wherein, with said accessory moduleattached at the in-cabin side of the windshield of the equipped vehicle,captured image data is processed at said control to determine a roadcondition of the road ahead of the equipped vehicle.
 30. The vehicularforward viewing image capture system of claim 26, wherein said vehicularforward viewing image capture system automatically compensates formisalignment of said imaging sensor.
 31. The vehicular forward viewingimage capture system of claim 30, wherein said vehicular forward viewingimage capture system determines misalignment of said imaging sensorresponsive at least in part to a focus of expansion ahead of thevehicle.
 32. The vehicular forward viewing image capture system of claim31, wherein said vehicular forward viewing image capture systemdetermines misalignment of said imaging sensor responsive todetermination of location and movement of another vehicle relative tothe focus of expansion as the equipped vehicle travels along a straightsection of the road.
 33. The vehicular forward viewing image capturesystem of claim 31, wherein said vehicular forward viewing image capturesystem determines misalignment of said imaging sensor responsive totracking movement of light sources through multiple frames of capturedimage data when the equipped vehicle travels along a straight section ofthe road.
 34. The vehicular forward viewing image capture system ofclaim 26, wherein the received vehicle data comprises (i) vehicle speeddata and (ii) vehicle trajectory data.
 35. The vehicular forward viewingimage capture system of claim 26, wherein the received vehicle datacomprises vehicle GPS data.
 36. The vehicular forward viewing imagecapture system of claim 26, wherein the received vehicle data comprisesvehicle pitch data.
 37. The vehicular forward viewing image capturesystem of claim 26, wherein the received vehicle data comprises vehicleyaw data.
 38. The vehicular forward viewing image capture system ofclaim 26, wherein said accessory module comprises said control and anelectrical connector for electrically connecting to a vehicle wiringsystem when said accessory module is attached at the in-cabin side ofthe windshield of the equipped vehicle.
 39. The vehicular forwardviewing image capture system of claim 26, wherein said accessory moduleis configured to removably attach at an attachment plate that is fixedlyattached at the in-cabin side of the windshield of the equipped vehicle.40. A vehicular forward viewing image capture system, said vehicularforward viewing image capture system comprising: an accessory moduleconfigured for attachment at an in-cabin side of a windshield of avehicle equipped with said vehicular forward viewing image capturesystem; wherein said accessory module comprises an imaging sensor, saidimaging sensor comprising a two-dimensional array of photosensorelements; wherein, with said accessory module attached at the in-cabinside of the windshield of the equipped vehicle, said imaging sensor hasa field of view through the windshield forward of the equipped vehicle;a control, said control comprising a digital processor for processingmultiple frames of image data captured by said imaging sensor; wherein,with said accessory module attached at the in-cabin side of thewindshield of the equipped vehicle, and while the equipped vehicle istraveling along a road, said control processes multiple frames ofcaptured image data to determine (i) presence of an object of interestin the forward field of view of said imaging sensor and (ii) movement ofthe object of interest present in the forward field of view of saidimaging sensor; wherein said control receives vehicle data via a vehiclecommunication bus; wherein the received vehicle data comprises (i)vehicle speed data and (ii) vehicle trajectory data; and wherein, withsaid accessory module attached at the in-cabin side of the windshield ofthe equipped vehicle, and responsive to the processing of multipleframes of captured image data and responsive to the received vehicledata, said control at least in part provides at least one selected fromthe group consisting of (a) traffic sign recognition, (b) traffic lightstatus detection, (c) adaptive cruise control and (d) pedestriandetection.
 41. The vehicular forward viewing image capture system ofclaim 40, wherein, with said accessory module attached at the in-cabinside of the windshield of the equipped vehicle, captured image data isprocessed at said control to determine a road condition of the roadahead of the equipped vehicle.
 42. The vehicular forward viewing imagecapture system of claim 40, wherein said vehicular forward viewing imagecapture system automatically compensates for misalignment of saidimaging sensor.
 43. The vehicular forward viewing image capture systemof claim 42, wherein said vehicular forward viewing image capture systemdetermines misalignment of said imaging sensor responsive at least inpart to a focus of expansion ahead of the vehicle.
 44. The vehicularforward viewing image capture system of claim 43, wherein said vehicularforward viewing image capture system determines misalignment of saidimaging sensor responsive to determination of location and movement ofanother vehicle relative to the focus of expansion as the equippedvehicle travels along a straight section of the road.
 45. The vehicularforward viewing image capture system of claim 43, wherein said vehicularforward viewing image capture system determines misalignment of saidimaging sensor responsive to tracking movement of light sources throughmultiple frames of captured image data when the equipped vehicle travelsalong a straight section of the road.
 46. The vehicular forward viewingimage capture system of claim 40, wherein the received vehicle datacomprises vehicle GPS data.
 47. The vehicular forward viewing imagecapture system of claim 40, wherein the received vehicle data comprisesvehicle pitch data.
 48. The vehicular forward viewing image capturesystem of claim 40, wherein the received vehicle data comprises vehicleyaw data.
 49. The vehicular forward viewing image capture system ofclaim 40, wherein said accessory module comprises said control and anelectrical connector for electrically connecting to a vehicle wiringsystem when said accessory module is attached at the in-cabin side ofthe windshield of the equipped vehicle.
 50. The vehicular forwardviewing image capture system of claim 40, wherein said accessory moduleis configured to removably attach at an attachment plate that is fixedlyattached at the in-cabin side of the windshield of the equipped vehicle.